Purported low mortality from coronary heart disease (CHD) in Eskimos (Greenland, Canadian or Alaskan) has been interpreted by many investigators as synonymous with the absence of or reduced amount of atherosclerotic lesions in the coronary arteries compared to populations with much CHD. The broad objectives of this proposed investigation are 1) to characterize the prevalence and the extent of atherosclerotic lesions (fatty streaks and raised lesions) in the coronary arteries and aorta in autopsied Alaskan natives (Aleuts, Indians, and Eskimos) and in non-natives dying of all causes, 2) to examine the relationship of omega-3 fatty acids and clinical risk factors to atherosclerosis in the two populations, and 3) to compare these findings with those studied using similar methodology in other populations such as the blacks and whites in New Orleans, Japanese, Norwegians and 19 ethnic groups in the International Atherosclerosis Project. The two important hypotheses to be tested are whether there are real differences in the prevalence and extent of atherosclerotic lesions in the coronaries and the aorta between Alaskan natives and non-natives and whether the extent of atherosclerotic lesions are related to omega-3 fatty acids in blood and tissues. Coronary arteries, aortas, blood, adipose tissue and liver will be collected at autopsy from 280 deceased Alaskan natives, approximately 70 cases per year, aged 5 years and above, dying of all causes and from a similar number of age- and sex-matched non-native Alaskans. Tested standardized methods of gross evaluation, histomorphometry, and chemistry will be used to characterize, measure and evaluate the prevalence and extent of atherosclerosis in arteries. Chemical methods for determination of blood and tissue lipids and gas liquid chromatographic methods for determination of fatty acids in various lipid fractions in plasma and tissues will be used. This study will establish the prevalence and extent of atherosclerotic lesions in arteries in Alaskan natives and will examine the relationship of omega-3 fatty acids to atherosclerosis. An understanding of this latter relationship will not only help to clarify the role of omega-3 fatty acids in atherosclerosis but also will help in making a decision whether to recommend to the general public the inclusion of fish oils, which contain large amounts of these fatty acids in the diet, for prevention and/or reduction of atherosclerotic heart disease.